Using metal complex compositions as gas generants

Abstract

Gas generating compositions and methods for their use are provided. Metal complexes are used as gas generating compositions. These complexes are comprised of a metal cation template, a neutral ligand containing hydrogen and nitrogen, and sufficient oxidizing anion to balance the charge of the complex. The complexes are formulated such that when the complex combusts, nitrogen gas and water vapor is produced. Specific examples of such complexes include metal nitrite ammine, metal nitrate ammine, and metal perchlorate ammine complexes, as well as hydrazine complexes. A binder and co-oxidizer can be combined with the metal complexes to improve crush strength of the gas generating compositions and to permit efficient combustion of the binder. Such gas generating compositions are adaptable for use in gas generating devices such as automobile air bags.

What is claimed is: 
     
       1. A method of inflating an inflatable air bag or balloon comprising generating substantially non-toxic gas by combusting an at least essentially azide-free gas generating, composition containing at least one metal ammine complex having transition metal cation or alkaline earth metal cation and at least one neutral ligand comprised of ammonia, and sufficient oxidizing anion to balance the charge of the metal cation, wherein said composition is formulated with at least one additional ingredient which comprises: (i) carbon powder,   (ii) a binder, or   (iii) up to about 50% by weight of an inorganic oxidizer, such that when the gas generating formulation combusts, a substantially non-toxic mixture of gases containing nitrogen gas and water vapor is produced; and     inflating said air bag or balloon using said gases.   
     
     
       2. A method according to claim 1, wherein said formulation consists essentially of hexaammine cobalt(III) nitrate; water-soluble binder; optionally carbon powder in an amount of 0.1 to 6% by weight of said formulation; and optionally, inorganic co-oxidizer in an amount less than 50% by weight of said formulation. 
     
     
       3. A method according to claim 1, wherein said metal ammine complex is at least one member selected from the group consisting of metal ammine nitrites, metal ammine nitrates and metal ammine perchlorates. 
     
     
       4. A method according to claim 1, wherein the metal cation is of a metal selected from the group consisting of manganese, magnesium, cobalt and zinc. 
     
     
       5. A method according to claim 1, wherein the combustion is capable of producing an excess of fuel, and wherein said formulation includes an effective amount of additional oxidizing agent for combusting during said generating step, and said oxidizing agent is other than said metal ammine complex and is at least one member selected from the group consisting of nitrates, nitrites, chlorates, perchlorates, peroxides, and metal oxides. 
     
     
       6. A method according to claim 1, wherein the combustion is capable of producing an excess of oxidizing species during the combustion, and wherein said formulation includes an effective amount of additional fuel for combusting during said generating step. 
     
     
       7. A method according to claim 1, wherein said formulation is in the form of pellets or granules. 
     
     
       8. A method according to claim 1, wherein said transition metal cation is a cobalt cation. 
     
     
       9. A method according to claim 1, wherein said binder is present in an amount of 0.5 to 12% by weight of the formulation. 
     
     
       10. A method according to claim 1, wherein said binder is present in an amount of 2 to 8% by weight of the formulation. 
     
     
       11. A method claim 1, wherein said binder comprises at least one naturally occurring gum. 
     
     
       12. A method according to claim 1, wherein said binder comprises guar gum or acacia gum. 
     
     
       13. A method according to claim 1, wherein said binder is present in an amount of 0.5 to 12% by weight of the formulation, and said binder comprises a naturally occurring gum. 
     
     
       14. A method according to claim 1, wherein said formulation contains carbon powder in an amount of 0.1% to 6% by weight of said formulation. 
     
     
       15. A method according to claim 10, wherein said formulation also contains 0.5 to 12% by weight of the formulation of a binder. 
     
     
       16. A method according to claim 1, wherein said formulation contains carbon powder in an amount of 0.3% to 3% by weight of said formulation. 
     
     
       17. A method according to claim 1, wherein said binder is present in an amount of 0.5 to 12% by weight of the formulation, said binder comprises a naturally occurring gum, and said formulation contains carbon powder in an amount of 0.1% to 3% by weight of said formulation. 
     
     
       18. A method according to claim 1, wherein said formulation contains at least one additive which comprises at least one member selected from the group consisting of burn rate modifiers, slag formers, release agents, coolants and NO x  reducing agents. 
     
     
       19. A method according to claim 1, wherein said formulation contains at least about 60% by weight, combined, of said complex and said oxidizing anion. 
     
     
       20. A method according to claim 1, wherein said formulation contains at least about 65% by weight, combined, of said complex and said oxidizing anion. 
     
     
       21. A method according to claim 1, wherein said formulation contains at least about 50% by weight but less than 100% by weight, combined, of said complex and said oxidizing anion. 
     
     
       22. A method according to claim 1, wherein said formulation contains at least about 50% to about 80% by weight, combined, of said complex and said oxidizing anion. 
     
     
       23. A method according to claim 1, wherein said inflatable airbag or balloon is part of a supplemental safety restraint system in an automobile.